JP2013205509A - Optical sheet, display device including the same, and manufacturing method of optical sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet capable of improving viewing angle characteristics at an end while maintaining contrast at a center part, an image display device including the optical sheet, and a manufacturing method of a sheet with improved contrast.SOLUTION: An optical sheet 10 comprises: a light transmissive base material 11; a plurality of unit light transmission parts 12a provided in parallel along a sheet surface; and a plurality of light absorption parts 13. Each light absorption part 13 includes a first end face 13a positioned on a side of the light transmissive base material 11, and a second end face 13b positioned opposite the end face 13a. The distances from the light transmissive base material 11 to the respective first end faces 13a are substantially equal to each other, and the height of the light absorption part 13 positioned at an end 10b of the optical sheet 10 is lower than that of the light absorption part 13. The optical sheet further comprises a coated part 14 that covers the second end face 13b of the light absorption part 13 positioned at least at the end 10b of the optical sheet 10, includes light transmissive resin, and has refractive index lower than that of the unit light transmission part.

Description

  The present invention relates to an optical sheet, a display device including the optical sheet, and a method for manufacturing the optical sheet.

  In recent years, with the widespread use of thin and large displays, the usages such as home televisions and commercial display devices have been diversified, and a high level of display image quality is being demanded.

  The optical sheet used for the display is also required to have a function for improving the transmittance and contrast. For this reason, for example, an optical sheet for improving contrast may be disposed on the display.

  Such an optical sheet includes a light transmissive substrate, a light transmissive portion having a plurality of unit light transmissive portions formed in parallel on the light transmissive substrate, and a unit light transmissive portion. And a light absorption part composed of a cured product of a composition for a light absorption part including an ionizing radiation curable resin composition and light absorption particles (see Patent Document 1). According to this optical sheet, image light can be emitted from the light transmission part, and external light and the like can be absorbed by the light absorption part, so that the contrast can be improved.

  By the way, this optical sheet is usually designed on the assumption that the observer views the display from the front direction in the center of the screen of the display. In some cases, the display is viewed from above or from the bottom.

  However, when the optical sheet is placed on the display and the screen is looked down from above, or when looking up at the screen, there is a problem that the top and bottom of the display becomes dark. Here, since the contrast and the viewing angle characteristic are in a trade-off relationship, when the viewing angle characteristic is improved, the contrast is lowered. On the other hand, not only when the observer looks down at the screen from above or looks up at the screen from below, but also when viewing the display from the front of the center of the display screen, It is necessary to maintain contrast.

JP 2009-31322 A

  The present invention has been made to solve the above problems. That is, an optical sheet that can improve the viewing angle characteristics at the end of the optical sheet while maintaining the contrast at the center of the optical sheet, an image display apparatus including the optical sheet, and a method for manufacturing the optical sheet are provided. For the purpose.

  As a result of intensive studies to improve the viewing angle characteristics at the end portion of the optical sheet, the present inventors have found that the distance from the light transmissive substrate to the end surface of the light absorbing portion on the light transmissive substrate side is substantially equal. In this case, the present inventors have found that the viewing angle characteristics change depending on the height of the light absorbing portion. The present invention has been completed based on such findings.

  According to one aspect of the present invention, the light transmissive substrate has a plurality of unit light transmissive portions provided in parallel along the sheet surface, and is provided on the light transmissive substrate. An optical sheet comprising a light transmission part and a plurality of light absorption parts provided between the unit light transmission parts, wherein each of the light absorption parts is a first end face located on the light transmissive substrate side; A second end face located on the opposite side of the first end face, and the distance from the light-transmitting substrate to the first end face in each of the light absorbing portions is substantially equal, and the unit light The height of the light absorption part located at the end of the optical sheet in the parallel direction of the transmission part is higher than the height of the light absorption part located in the central part of the optical sheet in the parallel direction of the unit light transmission part. The second end surface of the light absorbing portion that is low and at least located at the end portion of the optical sheet Cover, made of a light transmissive resin, and characterized by further comprising a cover portion having a refractive index lower than the refractive index of the light transmitting unit, the optical sheet is provided.

  According to another aspect of the present invention, there is provided a display device comprising: a display unit; and the optical sheet disposed on the viewer side with respect to the display unit.

  According to another aspect of the present invention, the light transmissive substrate has a plurality of unit light transmissive portions provided in parallel along the sheet surface, and is provided on the light transmissive substrate. A method for manufacturing an optical sheet comprising a light transmitting part and a plurality of light absorbing parts provided between the unit light transmitting parts, the optical sheet being provided on a light-transmitting substrate and parallel to the sheet surface A light transmitting portion having a plurality of unit light transmitting portions provided and a plurality of grooves provided between the unit light transmitting portions, and having substantially the same distance from the light transmitting base material to the bottom surface of the grooves And a light absorbing part composition containing an ionizing radiation curable resin composition and light absorbing particles on the surface of the light transmitting part, and the light absorbing part on the surface of the light transmitting part A step of filling the groove with the composition for a light absorbing part by scraping off the composition for a light, and for the light absorbing part Curing the composition to form a plurality of light absorbing portions between the unit light transmitting portions, wherein the light absorbing portion composition is supplied in the parallel direction of the unit light transmitting portions. Provided is a method for producing an optical sheet, which is performed so that the amount of the light absorbing portion composition supplied in the end portion of the light transmitting portion in the parallel direction of the unit light transmitting portions is smaller than the central portion of the portion. Is done.

  According to the optical sheet of one embodiment of the present invention and the display device of another embodiment, in each light absorbing portion, the distance from the light transmissive substrate to the first end face of the light absorbing portion is substantially equal, and unit light Since the height of the light absorption part located at the end of the optical sheet in the parallel direction of the transmission part is lower than the height of the light absorption part located in the center part of the optical sheet in the parallel direction of the unit light transmission part, the optical sheet The contrast can be maintained at the center of the optical sheet, and the viewing angle characteristics can be improved at the end of the optical sheet. Further, since the covering portion having the refractive index lower than the refractive index of the unit light transmitting portion is formed by covering the second end face of the light absorbing portion, made of a light transmitting resin, and at the end portion of the optical sheet. A decrease in contrast can be suppressed.

  According to the method for producing an optical sheet of another aspect of the present invention, a light transmitting part having a substantially equal distance from the light transmitting base material to the bottom surface of the groove is prepared, and the composition for the light absorbing part is supplied in units. Since the end of the light transmission part in the parallel direction of the unit light transmission part is performed so that the supply amount of the composition for the light absorption part is smaller than the central part of the light transmission part in the parallel direction of the light transmission part, At the end of the optical sheet, it is possible to form a light absorbing portion whose height is lower than the height of the light absorbing portion located at the center of the optical sheet. Thereby, contrast can be maintained at the center of the optical sheet, and viewing angle characteristics can be improved at the end of the optical sheet.

It is a top view of the optical sheet concerning an embodiment. It is sectional drawing when the optical sheet shown by FIG. 1 is cut | disconnected by the II line | wire. It is the figure which expanded the center part of the optical sheet shown by FIG. It is the figure which expanded the edge part of the optical sheet shown by FIG. It is a schematic block diagram of the other optical sheet which concerns on embodiment. It is a figure which shows the effect in the center part of the optical sheet which concerns on embodiment. It is a figure which shows the effect in the edge part of the optical sheet which concerns on embodiment. It is the figure which showed typically the manufacturing process of the optical sheet which concerns on embodiment. It is the figure which showed typically the manufacturing process of the optical sheet which concerns on embodiment. It is the figure which showed typically the formation process of the light transmissive part which concerns on embodiment. It is the figure which showed typically the supply process of the composition for light absorption parts which concerns on embodiment. It is sectional drawing when the die head shown in FIG. 11 is cut | disconnected by the II-II line. It is sectional drawing when the die head shown in FIG. 11 is cut | disconnected by the III-III line. It is the figure which showed typically the scraping process of the composition for light absorption parts which concerns on embodiment. It is a figure which shows the filling state of the composition for light absorption parts in the groove | channel located in the center part of the light transmissive part which concerns on embodiment. It is a figure which shows the filling state of the composition for light absorption parts in the groove | channel located in the edge part of the light transmissive part which concerns on embodiment. It is sectional drawing of the display apparatus provided with the optical sheet which concerns on embodiment. It is the graph showing the discharge amount ratio in each discharge position of the die head used when manufacturing the optical sheet which concerns on an Example. It is the graph showing the relative brightness | luminance with respect to the viewing angle of the center part and edge part of the optical sheet which concerns on an Example.

  Hereinafter, an optical sheet, a manufacturing method thereof, and an image display device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of the optical sheet according to the present embodiment, FIG. 2 is a cross-sectional view of the optical sheet shown in FIG. 1 taken along the line II, and FIG. 3 is an optical view shown in FIG. FIG. 4 is an enlarged view of a central portion of the sheet, and FIG. 4 is an enlarged view of an end portion of the optical sheet shown in FIG. FIG. 5 is a schematic configuration diagram of another optical sheet according to the present embodiment, FIG. 6 is a diagram illustrating operational effects in the central portion of the optical sheet according to the present embodiment, and FIG. 7 is an optical diagram according to the present embodiment. It is a figure which shows the effect in the edge part of a sheet | seat.

  The optical sheet 10 shown in FIG. 1 and FIG. 2 includes a light transmissive base material 11 and a plurality of unit light transmissive portions provided on the light transmissive base material 11 and provided in parallel along the sheet surface. The light transmission part 12 which has 12a, the some light absorption part 13 provided between the unit light transmission parts 12a, and the coating | coated part 14 are provided. Here, the “sheet surface” refers to a surface coinciding with the planar direction when the target optical sheet is viewed as a whole and globally.

(Light transmissive substrate)
The light transmissive substrate 11 is a layer serving as a base for forming the light transmissive portion 12. As the light transmissive substrate 11, a transparent resin film, a transparent resin plate, a transparent resin sheet, or transparent glass can be used. Transparent resin films include triacetate cellulose (TAC) film, polyester film such as polyethylene terephthalate (PET), diacetyl cellulose film, acetate butyrate cellulose film, polyethersulfone film, polyacrylic resin film, polyurethane resin film Polyester film, polycarbonate film, polysulfone film, polyether film, polymethylpentene film, polyether ketone film, (meth) acrylonitrile film, etc. can be suitably used. Among these, polyester films are preferably used. . Examples of the polyester film include polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, and polytrimethylene terephthalate.

(Light transmission part)
The light transmission part 12 is a sheet-like thing, and is comprised from the several unit light transmission part 12a as mentioned above. The plurality of unit light transmission portions 12a are arranged in parallel in the parallel direction D1 (array direction) shown in FIG. The light transmission portion 12 can have a width of 500 mm to 1500 mm and a height of 20 μm to 200 μm. The refractive index of the light transmission part can be 1.51 or more and 1.60 or less.

  The material constituting the light transmission part 12 is not particularly limited as long as it is a material that transmits light, but such a material can be composed of a cured product of a thermoplastic resin or an ionizing radiation curable resin composition. It is.

(Light absorption part)
As described above, the light absorbing portion 13 is provided between the unit light transmitting portions. As shown in FIG. 2, the light absorbing portion 13 includes a first end surface 13 a that is an end surface on the light transmissive substrate 11 side, and a second end surface 13 b that is an end surface opposite to the first end surface 13 a. And have. The second end surface 13b of the central portion 10a of the optical sheet 10 in the parallel direction D1 of the unit light transmitting portions 12 is planar as shown in FIGS. 2 and 3, but the second end surface 13b. May be concave. In addition, the second end surface 13b of the end portion 10b of the optical sheet 10 in the parallel direction D1 of the unit light transmitting portions 12 is concave as shown in FIGS. 2 and 4. The end surface 13b may be planar. Further, the width of the second end face 13b shown in FIGS. 3 and 4 is wider than the width of the first end face 13a, but the width of the second end face 13b and the width of the first end face 13a are as follows. It may be the same. 3 is inclined at the upper portion of the side surface 13c of the light absorbing portion 13 with respect to the normal direction N of the light-transmitting substrate 11 so that the width of the second end surface 13b is wider. Is larger than the inclination angle at the lower portion of the side surface 13c. The light absorbing portion 13 is not limited to the shape shown in FIG. 3. For example, the light absorbing portion 13 may be formed in a substantially trapezoidal shape, a substantially triangular shape, or a substantially rectangular shape that tapers toward the light transmissive substrate 11 side.

  In the light absorbing portion 13, the distance from the light transmissive substrate 11 to the first end face 13a is substantially equal from the central portion 10a to the end portion 10b of the optical sheet 10 (see the distance A in FIGS. 3 and 4). ). In the present specification, the “distance from the light transmissive substrate” means the distance from the interface between the light transmissive substrate and the light transmitting portion. Further, “substantially equal” means that the variation in distance from the light-transmitting substrate to the first end face is within 10%. The distance A is preferably 5 μm or more and 50 mm or less. If the distance A is within this range, the sheet-like light transmission part 12 can be formed reliably.

  The height B2 of the light absorbing portion 13 located at the end portion 10b of the optical sheet 10 shown in FIG. 4 is higher than the height B1 of the light absorbing portion 13 located at the central portion 10a of the optical sheet 10 shown in FIG. It is low. In the present specification, the “height of the light absorbing portion” means a distance from the first end surface to the second end surface. Further, when the second end surface is concave like the second end surface 13b of the end portion 10b of the optical sheet 10 shown in FIG. 4, the “height of the light absorbing portion” The distance from the first end surface to the most recessed position on the second end surface is meant (see height B2 in FIG. 4).

  The height B1 of the light absorbing portion 13 located at the central portion 10a of the optical sheet 10 is preferably 50 μm or more and 150 μm or less. The height B2 of the light absorbing portion 13 located at the end portion 10b of the optical sheet 10 is preferably 40 μm or more and 140 μm or less.

  The distance C from the surface of the unit light transmitting portion 12a located at the end portion 10b of the optical sheet 10 to the second end face 13b of the light absorbing portion 13 located at the end portion 10b of the optical sheet 10 shown in FIG. It is preferable that they are 1 micrometer or more and 10 micrometers or less. When the second end surface is concave like the second end surface 13b of the end portion 10b of the optical sheet 10 shown in FIG. 4, the “distance to the second end surface” The distance to the most concave position on the end face of 2 is meant (see distance C in FIG. 4). If the distance C is within this range, the viewing angle characteristics at the end portion 10b of the optical sheet 10 can be improved, while the light absorbing unit 13 located at the end portion 10 of the optical sheet 10 effectively transmits external light. Can be absorbed.

  The light absorption part 13 is comprised from the hardened | cured material of the composition for light absorption parts containing an ionizing radiation curable resin composition and a light absorption particle. It is preferable that the viscosity of the composition for light absorption parts is 500 mPa * s or more and 5000 mPa * s or less. If the viscosity of the composition for light absorption parts is this range, while being able to fill the composition for light absorption parts to the bottom of a groove | channel, the scraping property of the composition for light absorption parts will become favorable. In addition, the viscosity of the composition for light absorption parts is the value measured in 25 degreeC environment using the B-type viscometer.

  As the ionizing radiation curable resin composition, conventionally known ionizing radiation curable resin compositions can be used. For example, those having an acrylate functional group can be suitably used. Specifically, polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetals having a relatively low molecular weight can be used. Examples thereof include oligomers or prepolymers such as (meth) allylates of polyfunctional compounds such as resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols. Although depending on the material constituting the light transmission part, among these resins, a resin having a refractive index smaller than that of the material constituting the light transmission part may be selected.

  A reactive diluent may be added to the resin composition. Examples of the reactive diluent include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. Monofunctional monomers and polyfunctional monomers such as dimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) may be used. Examples include acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol di (meth) acrylate.

  In order to convert the ionizing radiation curable resin composition into an ultraviolet curable resin composition, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, tetramethylchuram mono as a photopolymerization initiator in the composition. A mixture of sulfides, thioxanthones, n-butylamine, triethylamine, poly-n-butylphosphine, or the like as a photosensitizer can be used. In particular, in the present invention, it is preferable to mix urethane acrylate as an oligomer and dipentaerythritol hexa (meth) acrylate as a monomer.

  The light absorbing particles preferably have an average particle diameter of 1 μm or more and 10 μm or less. When the average particle diameter of the light absorbing particles is within this range, the filling property of the light absorbing part composition into the groove of the light transmitting part can be further enhanced. The average particle diameter of the light absorbing particles means an arithmetic average diameter obtained by observing the light absorbing particles with an electron microscope.

  As the light absorbing particles, resin beads or glass beads may be light absorbing particles that can selectively absorb a specific wavelength according to the characteristics of the image light. Carbon black, graphite, fibrous carbon, black oxidation What knead | mixed colorants, such as metal salts, such as iron, dye, and a pigment, can be used. From the viewpoint of easy kneading of the colorant, it is preferable to use resin beads. As the resin beads, melamine beads, acrylic beads, acrylic-styrene beads, polycarbonate beads, polyethylene beads, polystyrene beads, polyvinyl chloride beads and the like can be suitably used. Further, urethane cross-linked fine particles and silicon-based beads can also be suitably used. These resin beads are preferably those having a refractive index difference of about 0.1 of the ionizing radiation curable resin composition described above. Also, as the resin before kneading the colorant, a transparent resin can be used, but it is preferable to use a resin colored with a pigment or a dye, and a specific wavelength is selectively selected according to the characteristics of the image light. However, resin beads colored in black are preferably used.

  Among the above-mentioned materials, carbon black can be preferably used as the colorant. The amount of carbon black kneaded into the resin beads is about 0.1 to 0.7 parts by mass, preferably 0.15 to 0.5 parts by mass, more preferably 1 part by mass of the resin beads. Is 0.2 to 0.35 parts by mass. When the amount of kneading of carbon black is more than 0.7 parts by mass, the resin beads may be easily broken. On the other hand, when the amount is less than 0.1 parts by mass, light absorbing particles having desired blackness can be obtained. There may not be. Carbon black having an average particle diameter of 10 to 500 nm can be suitably used. For example, furnace black, acetylene black, channel black, thermal black, carbon nanotube, carbon fiber and the like can be used. Commercially available products can also be used. For example, HCF series, MCF series, RCF series, LFF series (all manufactured by Mitsubishi Chemical Corporation), Vulcan series (made by Cabot Corporation), Ketjen series (Lion Corporation) Can be suitably used. Here, the average particle diameter means an arithmetic average diameter obtained by observing carbon black particles with an electron microscope.

  In order to improve the dispersibility of the light absorbing particles in the ionizing radiation curable resin composition, the light absorbing particles may be surface-treated. Examples of the surface treatment include hydrophilic treatment with a conventionally known silica coating and surface modification with plasma or the like.

  The composition for light absorption parts containing each component described above is prepared by mixing a predetermined amount of light absorption particles into an ionizing radiation curable resin composition and adding a polymerization initiator or the like as desired. The addition amount of the light absorbing particles is preferably in the range of 15 to 35% with respect to the total mass of the composition for the light absorbing portion, and by setting this range, an optical sheet with more excellent contrast can be realized. it can. If the light-absorbing particle content is too small, the light-shielding property of the light-absorbing part may be insufficient. If the light-absorbing particle content is too large, the resin beads may come into contact with each other, causing problems such as cracking and chipping. It tends to occur.

(Coating part)
The covering portion 14 is provided so as to cover at least the second end face 13 b of the light absorbing portion 13 located at the end portion 10 b of the optical sheet 10. The covering portion 14 may be provided so as to cover not only the light absorbing portion 13 located at the end portion 10 b of the optical sheet 10 but also the second end face 13 b in all the light absorbing portions 13.

  The covering portion 14 has a refractive index lower than that of the light transmitting portion 12. By making the refractive index of the covering portion 14 lower than the refractive index of the light transmitting portion 12, the light incident from the surface of the light transmitting portion 12 is totally reflected by the covering portion 14 and emitted from the light transmitting portion 12. it can. The refractive index of the covering portion 14 is preferably 1.49 or more and 1.58 or less.

  The covering portion 14 is made of a light transmissive resin. The light transmissive resin is not particularly limited as long as it is light transmissive and has a low refractive index. Examples of such a light-transmitting resin include a cured product of the ionizing radiation curable resin composition described in the above light absorbing part composition.

  In the optical sheet 10, the surface opposite to the surface on the light transmitting portion 12 side of the light transmitting base material 11 is exposed, but as shown in FIG. An adhesive layer 15 and a release layer 16 may be provided on the surface of the substrate 11 opposite to the surface on the light transmission part 12 side. The optical sheet 20 is the same as the optical sheet 10 except that the adhesive layer 15 and the release layer 16 are formed.

(Adhesive layer)
The adhesive layer 15 is for bonding the optical sheet 20 to the display unit of the display device. The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer 15 is not particularly limited as long as it can transmit light and appropriately adhere the optical sheet 20 to others. As an adhesive, an acrylic copolymer can be mentioned, for example.

(Peeling layer)
The release layer 16 is for preventing the adhesive layer 15 from coming into contact with others during handling, and is formed on the adhesive layer 6. Although it does not specifically limit as the peeling layer 16, For example, a polyethylene terephthalate (PET) resin etc. are mentioned.

  In the central portion 10a of the optical sheet 10, the image light L1 incident on the light transmitting portion 12 shown in FIG. 6 is totally reflected at the boundary surface between the unit light transmitting portion 12a and the light absorbing portion 13, and the light transmitting base. The light is emitted to the observer side through the material 11. Further, a part of the external light L3 incident on the optical sheet 10 from the observer side is absorbed by the light absorption unit 13. For this reason, the contrast can be maintained in the central portion 10 a of the optical sheet 10.

  At the end portion 10b of the optical sheet 10, the height B2 of the light absorbing portion 13 is lower than the height B1 at the central portion 10a of the optical sheet 10. Moreover, since the coating | coated part 14 is comprised from the transparent resin, it can permeate | transmit light. Therefore, the image light L2 shown in FIG. 7 is transmitted through the covering portion 14 and emitted to the viewer side. On the other hand, in the central portion 10 a of the optical sheet 10, the image light L <b> 2 is absorbed by the light absorbing unit 13. Thereby, in the edge part 10b of the optical sheet 10, a viewing angle characteristic can be improved rather than the center part 10a of the optical sheet 10. FIG.

  Further, since the refractive index of the covering portion 14 is lower than the refractive index of the light transmitting portion 12, the image light L1 shown in FIG. 7 is totally reflected at the boundary surface between the unit light transmitting portion 12a and the covering portion 14 to transmit the light. The light is emitted to the observer side through the conductive substrate 11. Further, a part of the external light L3 incident on the optical sheet 10 from the observer side is absorbed by the light absorption unit 13. For this reason, in the edge part 10b of the optical sheet 10, the fall of contrast can be suppressed.

  The optical sheets 10 and 20 can be arrange | positioned on the display part of a display apparatus, for example. Specifically, the optical sheet can be used as an optical filter for a display device, for example. Examples of the display unit of the display device include a plasma display, a liquid crystal display, an organic EL display, a field emission display (FED), a surface conduction electron-emitting device display (SED), and a projection television.

<Optical sheet manufacturing method>
Such an optical sheet 10 can be manufactured by the following method. FIG. 8 and FIG. 9 are diagrams schematically illustrating the manufacturing process of the optical sheet according to the present embodiment, and FIG. 10 is a diagram schematically illustrating the process of forming the light transmission portion according to the present embodiment. FIG. 11 is a view schematically showing a supply process of the composition for a light absorbing portion according to this embodiment. 12 is a cross-sectional view when the die head shown in FIG. 11 is cut along line II-II, and FIG. 13 is a cross-sectional view when the die head shown in FIG. 11 is cut along line III-III.

  First, on the light transmissive substrate 11, a light transmissive portion 12 having a plurality of unit light transmissive portions 12a provided in parallel along the sheet surface and grooves 12b formed between the unit light transmissive portions 12a. Is formed (FIG. 8A). The groove 12b can have a bottom surface width of 2 μm to 10 μm, an opening surface width of 5 μm to 20 μm, and a depth of 50 μm to 150 μm. The groove 12b shown in FIG. 8A has an inclination angle at the upper part of the side surface of the groove 12b with respect to the normal direction N of the light-transmitting substrate 11 so that the width of the opening surface becomes wider. It is larger than the inclination angle. The groove 12b is not limited to the shape shown in FIG. 8A, and may be formed in, for example, a substantially trapezoidal shape, a substantially V shape, or a substantially rectangular shape that tapers toward the light transmissive substrate 11 side. .

  The formation method of the light transmission part 12 changes with kinds of resin to be used. For example, when the light transmission part 12 is formed using a transparent thermoplastic resin, a hot press method or an injection molding method for pressing a heated mold against the thermoplastic resin, or a thermoplastic resin monomer is injected into the mold Then, the light transmitting portion 12 can be formed by a casting method for polymerization and solidification. In the case of using an ionizing radiation curable resin, particularly an ultraviolet curable resin, the light transmitting portion 12 is formed by a so-called UV method in which the resin is injected into a mold and irradiated with ultraviolet rays to be cured. Can do. Among these methods, in the present invention, the UV method excellent in mass productivity can be suitably used. According to the UV method, the light transmission part 12 can be continuously manufactured using a mold roll.

  Specifically, for example, as shown in FIG. 10, a light transmissive substrate is provided between a mold roll 30 having a groove corresponding to the shape of the unit light transmitting portion 12 a at a predetermined pitch and a nip roll 31. 11 is sent. The arrows in FIG. 10 represent the direction in which the light transmissive substrate 11 is fed. In accordance with the feeding of the light transmissive base material 11, the light transmissive part composition 33 including, for example, an ionizing radiation curable resin composition from the supply part 32 between the mold roll 30 and the light transmissive base material 11. Continue to supply droplets. When supplying the light transmissive part composition 33 from the supply part 32 onto the light transmissive base material 11, the light transmissive part composition 33 accumulated between the mold roll 30 and the light transmissive base material 11. A composition reservoir 34 is formed. By forming the composition reservoir 34, the light transmissive portion composition 33 spreads in the width direction of the light transmissive substrate 11.

  The composition 33 for light transmissive part supplied between the mold roll 30 and the light transmissive substrate 11 as described above is light transmissive due to the pressing force between the mold roll 30 and the nip roll 31. It is filled between the base material 11 and the mold roll 30. Thereafter, the light transmitting portion composition 33 is irradiated with ultraviolet rays by the ionizing radiation irradiation device 35, and the light transmitting portion composition 33 is cured to form the light transmitting portion 12. After forming the light transmission part 12, the light transmission part 12 is peeled off from the mold roll 30 through the peeling roll 36.

  In addition, it is preferable that the surface of the groove | channel 12b of the light transmissive part 12 is hydrophilized before the next filling process of the composition for light absorption parts. By applying a hydrophilic treatment to the surface of the groove 12b, it becomes easier to fill the groove 12b with the composition for the light absorbing portion, and the ink filling rate is improved. The hydrophilic treatment can be performed using a conventionally known method. Examples thereof include dry processes such as low-pressure plasma treatment, atmospheric pressure plasma treatment, corona treatment, ultraviolet irradiation treatment, and excimer lamp treatment, and wet processes such as alkali treatment with sodium hydroxide, potassium hydroxide, ethanolamine, and the like. Among these, atmospheric pressure plasma treatment is preferable from the viewpoint of production efficiency.

  After the light transmissive part 12 is formed on the light transmissive substrate 11, the light absorbing part composition 17 is filled in the groove 12b (FIG. 8B). Since the composition 17 for light absorption parts is the same as the composition for light absorption parts demonstrated above, description shall be abbreviate | omitted.

  Filling the groove 12b with the composition 17 for the light absorbing portion can be performed using the optical sheet manufacturing apparatus 40 shown in FIG. The manufacturing apparatus 40 includes a transport device 50 and a supply device 60 shown in FIG. 11, and a scraping member 80 shown in FIG.

  The conveyance apparatus 50 is for conveying the light transmission part 12 with the light transmissive base material 11 to one direction, and is comprised from the conveyance roll etc. As shown in FIG. Although the line speed (conveyance speed) of the conveying apparatus 50 is based also on the supply speed of the composition 17 for light absorption parts, it is preferable that it is 1-50 m / min.

  The supply device 60 is for supplying the light absorbing portion composition 17 to the surface of the light transmitting portion 12. It is preferable that the supply speed | rate of the composition 17 for light absorption parts by the supply apparatus 60 is 0.5-10L / min.

  From the supply device 60, the end part 12d of the light transmission part 12 in the parallel direction D1 of the unit light transmission part 12a absorbs light more than the central part 12c of the light transmission part 12 in the parallel direction D1 of the unit light transmission part 12a. The light absorbing portion composition 17 is supplied so that the supply amount (discharge amount) of the portion composition 17 is reduced.

  The supply device 60 includes a die head 61 and a supply system 62 that supplies the light absorbing portion composition 17 to the die head 61. The die head 61 is disposed on the light transmission portion 12 so that the longitudinal direction D2 of the die head 61 is the width direction D3 of the light transmission portion 12 as shown in FIG.

  12 and 13, the die head 61 is formed in the injection head 63 of the light absorbing portion composition 17, the discharge port 64 of the light absorbing portion composition 17, and the die head 61. 63 and a manifold 65 extending in the longitudinal direction D2 of the die head 61, and a slit 66 formed in the die head 61 and communicating with the manifold 65 and the discharge port 64.

  Such a die head 61 can be constituted by, for example, a pair of die blocks 67 and 68 disposed so as to face each other, and a shim plate 69 interposed between the die blocks 67 and 68. The die blocks 67 and 68 are fixed by fastening the peripheral edges of the die blocks 67 and 68 with a bolt 70 or the like except for the discharge port 64 side. A bolt hole is also formed in the shim plate 69, and the shim plate 69 is also fixed together with the die blocks 67 and 68.

  An inlet 63 shown in FIG. 13 communicates with the central portion of the manifold 65, and a supply system 62 is connected to the inlet 63. The discharge port 64 shown in FIGS. 12 and 13 is formed on the lower surface of the die head 61.

  The slit 66 guides the light absorbing portion composition 17 extruded from the manifold 65 to the discharge port 64. The slit 66 is a space sandwiched between the slit forming surfaces 67 a and 68 a of the die blocks 67 and 68. The interval between the slits 66 can be adjusted by the thickness of the shim plate 69.

  The manifold 65 is for spreading the light absorbing portion composition 17 in the longitudinal direction D2 of the die head 61 (the width direction D3 of the light transmitting portion 12). The manifold 65 shown in FIG. 12 is formed only on the die block 67, but the manifold 65 may be formed on at least one of the die blocks 67 and 68. The total length of the manifold 65 can be 800 mm or more and 2000 mm or less.

  As shown in FIG. 13, the manifold 65 has a shape that is linear. By using the die head 61 having such a manifold 65, the supply amount (discharge amount) of the light absorbing portion composition 17 is more at the end portion 12d of the light transmitting portion 12 than at the central portion 12c of the light transmitting portion 12. The composition for a light absorption part can be supplied so that there may be few. That is, since the periphery of the die head 61 is fixed by the bolt 70 except for the discharge port 64 side, when the pressure in the die head 61 is increased in order to discharge the light absorbing portion composition 17 from the die head 61, the die head Although the center part of 61 swells, the edge part of the die head 61 hardly swells. Thereby, the composition 17 for the light absorption part from the edge part of the die head 61 becomes smaller than the supply amount of the composition 17 for the light absorption part from the center part of the die head 61.

  The end portion 65 a of the manifold 65 is at a position corresponding to the end portion 12 d of the light transmission portion 12, and the central portion 65 b of the manifold 65 is at a position corresponding to the central portion 12 c of the light transmission portion 12. Since the die head 61 shown in FIG. 11 is disposed on the light transmitting portion 12, the end portion 65a of the manifold 65 is located on the end portion 12d of the light transmitting portion 12, and the central portion 65b of the manifold 65 is the light transmitting portion. It is located on the central part 12 c of the transmission part 12.

  The cross-sectional shape of the manifold 65 shown in FIG. 13 is substantially constant from the central portion 65b to the end portion 65a. The cross-sectional shape of the manifold 65 can be rectangular, circular, or arcuate.

  When the cross-sectional shape of the manifold 65 is circular or arcuate, the radius of the cross-section of the manifold 65 is preferably 3 mm or more and 10 mm or less, and more preferably 4 mm or more and 7 mm or less. By setting the radius of the manifold 65 within this range, the pressure in the manifold 65 can be further increased, so that the composition for the light absorbing portion can be pushed out from the manifold 65 more. Since the die head manifold generally used for manufacturing this optical sheet has a rectangular shape with a cross section of 30 mm × 19 mm, the manifold is cut off as compared with the commonly used manifold. It can be said that the area is small.

  The scraping member 80 shown in FIG. 14 is disposed downstream of the supply position of the light absorbing portion composition 17 by the supply device 60. The scraping member 80 includes a scraping blade 81 that scrapes the composition 17 for light absorbing portion supplied onto the surface of the light transmitting portion 12, a holder 82 that holds the scraping blade 81, and the like.

  The scraping blade 81 is disposed so as to be orthogonal to the extending direction of the groove 12b. The scraping blade 81 may be composed of two scraping blades.

  The scraping blade 81 is a thin plate, and the thickness of the scraping blade 81 can be about 200 μm. As the scraping blade 81, for example, a doctor blade or the like can be used. The angle of the tip of the scraping blade 81 with respect to the surface of the light transmission part 12 is preferably 40 ° to 70 °, and more preferably 50 ° to 65 °. The reason why this angle range is preferable is that, within this angle range, the scraping of the light-absorbing part composition 17 becomes better, and the scraping blade 81 in contact with the light-absorbing part composition 17 The area does not become extremely small, and scraping defects such as black stripes hardly occur.

  Using such a manufacturing apparatus 40 and the light absorbing portion composition 17, the light absorbing portion composition 17 is filled in the groove 12 b of the light transmitting portion 12. Here, as described above, in the die head 61, the supply amount of the light absorbing portion composition 17 from the end of the die head 61 is greater than the supply amount of the light absorbing portion composition 17 from the center portion of the die head 61. Therefore, the height of the light absorbing portion composition 17 shown in FIG. 16 filled in the groove 12b located at the end portion 12d of the light transmitting portion 12 is located at the central portion 12c of the light transmitting portion 12. It becomes lower than the height of the composition 17 for light absorption parts shown by FIG. 15 with which the groove | channel 12b was filled.

  Specifically, first, as illustrated in FIG. 11, the sheet-shaped light transmission unit 12 is moved together with the light-transmitting base material 11 by the conveyance device 50 with respect to the supply device 60. The light absorbing portion composition 17 is continuously supplied from the die head 61 to the surface. And the composition 17 for light absorption parts on the surface of the light transmissive part 12 is scraped off by the scraping member 80 shown in FIG. As a result, the groove 12 b is filled with the light absorbing portion composition 17 and the excess light absorbing portion composition 17 present on the surface of the light transmitting portion 12 is scraped off.

  After the groove 12b is filled with the light absorbing portion composition 17, ionizing radiation is emitted to cure the light absorbing portion composition 17 in the groove 12b, thereby forming a plurality of light absorbing portions 13 (FIG. 8). (C)). As a curing method of the composition 17 for light absorption parts, it can harden | cure by the normal curing method, ie, irradiation of an electron beam or an ultraviolet-ray. For example, in the case of electron beam curing, 50 to 50 emitted from various electron beam accelerators such as a Cockloft Walton type, a bandegraph type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type An electron beam having an energy of 1000 keV, preferably 100 to 300 keV is used. In the case of ultraviolet curing, ultraviolet rays emitted from rays such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. Available.

  After forming the light absorbing portion 13, at least on the second end surface 13b of the light absorbing portion 13 located at the end portion 12d of the light transmitting portion 12, and in the region within the groove 12b, the ionizing radiation curable resin composition 18 is filled (FIG. 9A).

  Specifically, from a supply device similar to the supply device 60 shown in FIG. 11, the ionizing radiation curable resin composition 18 having light transparency in a state after curing is supplied onto the surface of the light transmission unit 12, Thereafter, the ionizing radiation curable resin composition 18 on the surface of the light transmitting portion 12 is scraped by a member similar to the scraping member 80. Here, as for the light absorption part 13 located in the edge part 12d of the light transmissive part 12, the position of the 2nd end surface 13b exists in a position lower than the opening surface of the groove | channel 13a. Therefore, by supplying the ionizing radiation curable resin composition 18 on the surface of the light transmissive part 12 and scraping off the ionizing radiation curable resin composition 18 on the surface of the light transmissive part 12, the end of the light transmissive part 12 is obtained. The ionizing radiation curable resin composition 18 can be filled in the region in the groove 12b on the second end face 13b of the light absorbing portion 13 located in the portion 12d. In the light absorbing portion other than the light absorbing portion 13 located at the end portion 12d of the light transmitting portion 12, if the position of the second end surface 13b is lower than the opening surface of the groove 13a, this step, The ionizing radiation curable resin composition 18 is filled in the region in the groove 12b on the second end face 13b of the light absorbing portion 13.

  After the ionizing radiation curable resin 18 is filled in the region in the groove 12b on the second end face 13b of the light absorbing portion 13 located at the end 12d of the light transmitting portion 12, the ionizing radiation is emitted. Then, the ionizing radiation curable resin composition 18 in the groove 12b is cured to form a covering portion 14 that covers the second end face 13b of the light absorbing portion 13 located at the end portion 12d of the light transmitting portion 12 (FIG. 9). (B)). Thereby, the optical sheet 10 is formed.

<Display device>
Hereinafter, the example which attached the optical sheet by this invention to the display part of the display apparatus is demonstrated. FIG. 17 is a cross-sectional view of a display device including the optical sheet according to the present embodiment. A display device 90 shown in FIG. 17 includes the optical sheet 10 manufactured by the above-described manufacturing method. The optical sheet 10 is affixed to the display unit 91 of the display device 90 via the adhesive layer 92 so that the light transmissive substrate 11 is on the viewer side. On the viewer side of the optical sheet 10, a functional layer 93 having functions such as antistatic properties, antireflection properties, and antiglare properties is disposed. The functional layer 93 may be composed of a plurality of layers.

  In order to describe the present invention in detail, the following examples will be described.

  First, the composition for light transmission parts, the composition for light absorption parts, and the composition for coating | covering parts of the following compositions were prepared.

(Composition for light transmission part)
Bisphenol A-ethylene oxide 2 mol adduct 41 parts by mass, isophorone diisocyanate 14.0 parts by mass, and bismuth tri (2-ethylhexanoate) (2-ethylhexanoic acid 50% solution)) 0.02 mass as urethanization catalyst The urethane acrylate oligomer obtained by adding 5 parts by mass of 2-hydroxyethyl acrylate and reacting at 80 ° C. for 5 hours was used as a photocurable prepolymer. . This urethane acrylate oligomer 32, 0 parts by mass, 10.0 parts by mass of phenoxyethyl acrylate (molecular weight 192) as a photocurable monomer, and 30.0 masses of diacrylate (molecular weight 512) of EO4 mol adduct of bisphenol A And 0.03 parts by mass of a tetradecanol-ethylene oxide 10-mole adduct as a mold release agent (monoester / diester = molar ratio 1/1), and a tearylamine ethylene oxide 15-mole adduct As a photopolymerization initiator, 02 parts by mass, 1 part of 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by BASF Japan Ltd.) and 3 parts by mass were mixed and homogenized to obtain a composition for a light transmission part. . In addition, this composition for light transmission parts was applied with a thickness of 10 μm, and cured by irradiating with 800 mJ / cm ² of ultraviolet light with a high-pressure mercury lamp, and using a multi-wavelength Abbe refractometer DR-M4 (manufactured by Atago Co., Ltd.). The refractive index measured at 589 nm was 1.550.

(Composition for light absorbing part)
As a photocurable prepolymer, ethylene oxide, 2,2 ′-[(1-methylethylidene) bis (4,1-phenyleneoxymethylene)] bis-, homopolymer, 20.0 parts by mass of di-2-propenoate, As reactive diluent monomers, 20.0 parts by mass of 2-phenoxyethyl acrylate, 20.0 parts by mass of α-acryloyl-ω-phenoxypoly (oxyethylene), and 2- {2- [2- (acryloyloxy) ( Methyl) ethoxy] (methyl) ethoxy} (methyl) ethyl acrylate 13.0 parts by mass, and light-absorbing particles containing 25% carbon black having an average particle size of 4.0 μm (manufactured by Ganz Kasei Co., Ltd.) ) 20.0 parts by mass and 1-hydroxycyclohexyl phenyl ketone (trade name: Irgaki as photopolymerization initiator) A 184, and Ciba Specialty Chemicals Co., Ltd.) 7.0 parts by mass, were mixed to obtain a light absorbing portion for composition was homogenized. In addition, this light-absorbing part composition was applied at a thickness of 10 μm, cured by irradiating an ultraviolet ray of 800 mJ / cm ² with a high-pressure mercury lamp, and a multi-wavelength Abbe refractometer DR-M4 (manufactured by Atago Co., Ltd.) was used. The refractive index measured at 589 nm was 1.540.

(Composition for coating part)
As a photocurable prepolymer, ethylene oxide, 2,2 ′-[(1-methylethylidene) bis (4,1-phenyleneoxymethylene)] bis-, homopolymer, 20.0 parts by mass of di-2-propenoate, As reactive diluent monomers, 20.0 parts by mass of 2-phenoxyethyl acrylate, 20.0 parts by mass of α-acryloyl-ω-phenoxypoly (oxyethylene), and 2- {2- [2- (acryloyloxy) ( 13.0 parts by mass of methyl) ethoxy] (methyl) ethoxy} (methyl) ethyl acrylate and 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator 7 0.0 part by mass was mixed and homogenized to obtain a coating composition. The coating composition was applied at a thickness of 10 μm, cured by irradiating with 800 mJ / cm 2 of ultraviolet light with a high-pressure mercury lamp, and 589 nm using a multiwavelength Abbe refractometer DR-M4 (manufactured by Atago Co., Ltd.). A refractive index of 1.540 was measured.

<Example>
A composition for a light transmitting part having the above composition is supplied onto a polyethylene terephthalate substrate (Toyobo Co., Ltd., A4300, thickness 100 μm, width 1400 mm), and the light transmitting part composition is cured to form a plurality of grooves on the surface. Were formed in parallel, and a light transmission portion having a width of 1400 mm was formed. The width of the opening surface of the groove was 10 μm, the width of the bottom surface of the groove was 4 μm, and the depth of the groove was 94 μm. Further, the distance from the polyethylene terephthalate substrate to the bottom surface of the groove was 25 μm.

  Next, using the manufacturing apparatus described in the embodiment, the light absorbing part composition having the above composition was filled in the groove of the light transmitting part. Specifically, the light transmission unit is continuously supplied to the surface of the light transmission unit at a supply speed of 5 L / min from the die head of the supply device while moving the light transmission unit together with the polyethylene terephthalate substrate at a line speed of 10 m / min. Then, using a metal doctor blade as a scraping blade, the light absorbing portion composition on the surface of the light transmitting portion was scraped off.

  Here, the die head used in the examples is formed in the die head, and is formed in the die head, and is in the longitudinal direction of the die head. And a slit formed in the die head and communicating with the manifold and the discharge port. Specifically, the manifold or the like is formed by combining a pair of die blocks and a shim plate interposed between the die blocks. The manifold had a total length of 1440 mm, and the manifold extended in a straight line from one end to the other end. The slit had a slit width of 1440 mm and a slit interval of 0.2 mm.

  The light absorbing part was formed by filling the groove of the light transmitting part with the light absorbing part composition and then irradiating the light absorbing part composition with ultraviolet rays to cure the light absorbing part composition. The height of the light absorption part located at the end of the light transmission part in the parallel direction of the unit light transmission part is 3 μm higher than the height of the light absorption part located in the center part of the light transmission part in the parallel direction of the unit light transmission part. It was low. Specifically, the light absorbing portion located at the center of the optical sheet is formed up to the opening surface of the groove, but the light absorbing portion located at the end of the optical transmitting portion is 3 μm lower than the opening surface of the groove. It was only formed up to the position.

  Next, using the same production apparatus as described above, the composition for the covering portion having the above composition was filled at least on the light absorbing portion located at the end of the light transmitting portion and in the groove of the light transmitting portion. Specifically, while moving the light transmission part and the light absorption part together with the polyethylene terephthalate base material at a line speed of 10 m / min, the surface of the light transmission part is supplied from the die head of the supply device at a supply speed of 5 L / min. The composition for covering portion on the surface of the light transmitting portion was scraped off using a metal doctor blade as a scraping blade.

  The composition for a light absorption part is irradiated with ultraviolet rays on the composition for a coating part after filling the composition for the coating part on the light absorption part located at the end of the light transmission part and in the groove of the light transmission part. Was cured to form a coating. Thereby, the optical sheet which concerns on an Example was produced.

(Discharge rate measurement)
When producing the optical sheet according to the example, the discharge amount of the composition for a light absorbing portion discharged from the die head in advance was measured at each position in the longitudinal direction of the die head at the discharge port. The central portion of the discharge port was located immediately below the central portion of the manifold, and the end portion of the discharge port was located immediately below the end portion of the manifold.

  FIG. 18 is a graph showing the discharge amount ratio at the discharge amount measurement position of the die head used when manufacturing the optical sheet according to the example. Here, the “discharge amount measurement position” on the horizontal axis of the graph is the position in the width direction of the die head, the discharge amount measurement position 1 is one end of the discharge port, and the discharge amount measurement position 14 is the other end of the discharge port. It was the end. In addition, the “discharge amount ratio” on the vertical axis of the graph means that the discharge amount at the center of the discharge amount measurement position (discharge position 8 in the graph) is 100%.

  As shown in the graph of FIG. 18, in the die head used in the manufacture of the optical sheet according to the example, the discharge amount of the composition for the light absorbing portion discharged from the end portion of the discharge port is the central portion of the discharge port. It was small compared with the discharge amount of the composition for light absorption parts discharged from.

  From this result, when a die head having a straight manifold from one end of the manifold to the other end is used, the discharge amount of the light absorbing portion composition at the end of the discharge port is It was confirmed that the amount can be reduced as compared with the discharge amount of the composition for the light absorbing portion in the central portion.

(Viewing angle characteristic evaluation)
Viewing angle characteristics were evaluated using the optical sheet according to the example. Viewing angle characteristic evaluation is to measure the relative luminance at the center and the edge of the screen of the plasma display while changing each viewing angle, and obtain the angle corresponding to 1/2 viewing angle and 1/3 viewing angle from the measurement result. It went by. "Viewing angle" means the vertical tilt angle with respect to the normal from the center of the screen at the center of the screen, and up and down with respect to the normal from the center of the screen edge at the edge of the screen. Means the inclination angle of. “Relative luminance” means the ratio (%) of the luminance when the optical sheet is arranged with respect to the luminance when the optical sheet is not arranged on the screen of the plasma display. The relative luminance is 100% when the optical sheet is not arranged on the screen of the plasma display. “1/2 viewing angle” means a viewing angle at which a relative brightness that is ½ of the front relative brightness is obtained, and “1/3 viewing angle” means 1/3 of the front relative brightness. The viewing angle at which the relative luminance is obtained. The luminance was measured at each angle with an automatic variable angle photometer (Murakami Color Research Laboratory, GP-500).

(Contrast evaluation)
Contrast evaluation was performed using the optical sheet which concerns on an Example. Contrast evaluation was performed at the screen center and the screen edge of the plasma display, respectively. Specifically, first, in a state where no optical sheet is arranged on the screen of the plasma display, external light is irradiated at an angle of 45 degrees toward the center of the screen so that the illuminance is 150 lx. In the front, the luminance when the screen was displayed in white (white luminance) and the luminance when the screen was displayed in black (black luminance) were measured. The value obtained by dividing the white luminance by the black luminance was taken as the contrast at the center of the screen. Next, with the optical sheet placed on the screen of the plasma display, external light is irradiated at an angle of 45 degrees toward the center of the screen so that the illuminance is 150 lx, and the screen is whitened in front of the center of the screen. The brightness when displayed (white brightness) and the brightness when displayed black (black brightness) were measured. Then, the white luminance was divided by the black luminance, and the contrast in a state where the optical sheet was arranged on the screen of the plasma display was obtained. And the ratio (%) of the state which has arrange | positioned the optical sheet with respect to the contrast of the state which has not arrange | positioned the optical sheet on the screen of the plasma display in the front of the screen center part was calculated | required. The contrast is 100% when no optical sheet is arranged on the screen of the plasma display. By the same method, the ratio (%) of the contrast in the state where the optical sheet is arranged to the contrast in the state where the optical sheet is not arranged on the screen of the plasma display is obtained at the screen edge of the plasma display.

表１および図１９に示されるように、コントラストにおいては、プラズマディスプレイの画面中央部の方が画面端部よりも高かった。また、表１に示されるように、１／２視野角および１／３視野角においては、プラズマディスプレイの画面端部の方が、画面中央部よりも高かった。この結果から、実施例に係る光学シートによれば、光学シートの中央部におけるコントラストが維持されつつ、光学シートの端部における視野角特性が向上することが確認された。 The results will be described below. FIG. 19 is a graph showing the relative luminance with respect to the viewing angle of the central portion and the end portion of the optical sheet according to the example.

As shown in Table 1 and FIG. 19, in contrast, the center of the screen of the plasma display was higher than the edge of the screen. Further, as shown in Table 1, at the 1/2 viewing angle and 1/3 viewing angle, the screen edge of the plasma display was higher than the center of the screen. From this result, according to the optical sheet which concerns on an Example, it was confirmed that the viewing angle characteristic in the edge part of an optical sheet improves, maintaining the contrast in the center part of an optical sheet.

DESCRIPTION OF SYMBOLS 10, 20 ... Optical film 10a ... Center part 10b ... End part 11 ... Light transmissive base material 12 ... Light transmission part 12a ... Unit light transmission part 12b ... Groove 12c ... Center part 12d ... End part 13 ... Light absorption part 13a ... 1st end surface 13b ... 2nd end surface 14 ... Covering part 17 ... Composition for light absorption parts

Claims (7)

A light transmissive substrate, a plurality of unit light transmissive portions provided in parallel along the sheet surface, and the light transmissive portions provided on the light transmissive substrate, and the unit light transmissive portions An optical sheet comprising a plurality of light absorbing portions provided therebetween,
Each of the light absorbing portions has a first end face located on the light transmissive substrate side, and a second end face located on the side opposite to the first end face,
The distance from the light transmissive substrate to the first end face in each light absorbing portion is substantially equal,
The height of the light absorbing part located at the end of the optical sheet in the parallel direction of the unit light transmitting part is the height of the light absorbing part located in the central part of the optical sheet in the parallel direction of the unit light transmitting part. Lower than the height,
A covering portion that covers at least the second end surface of the light absorbing portion located at the end portion of the optical sheet, is made of a light-transmitting resin, and has a refractive index lower than that of the light transmitting portion; An optical sheet comprising the optical sheet.   The distance from the surface of the unit light transmitting portion located at the end of the optical sheet to the second end face of the light absorbing portion located at the end of the optical sheet is 1 μm or more and 10 μm or less. The optical sheet according to claim 1.   The optical sheet according to claim 1 or 2, wherein a refractive index of the covering portion is 1.49 or more and 1.58 or less, and a refractive index of the light transmission portion is 1.51 or more and 1.60 or less. A display unit;
A display device comprising: the optical sheet according to claim 1, which is disposed closer to an observer than the display unit. A light transmissive substrate, a plurality of unit light transmissive portions provided in parallel along the sheet surface, and the light transmissive portions provided on the light transmissive substrate, and the unit light transmissive portions A method for producing an optical sheet comprising a plurality of light absorbing portions provided therebetween,
A plurality of unit light transmitting portions provided on the light transmissive substrate and provided in parallel along the sheet surface; and a plurality of grooves provided between the unit light transmitting portions; A step of preparing a light transmission portion having a substantially equal distance from the transparent substrate to the bottom surface of the groove;
A light absorbing part composition containing an ionizing radiation curable resin composition and light absorbing particles is supplied to the surface of the light transmitting part, and the light absorbing part composition on the surface of the light transmitting part is scraped off. A step of filling the groove with the composition for a light absorbing part,
Curing the light absorbing portion composition, and forming a plurality of light absorbing portions between the unit light transmitting portions,
The composition for the light absorbing portion is supplied at the end of the light transmitting portion in the parallel direction of the unit light transmitting portion rather than the central portion of the light transmitting portion in the parallel direction of the unit light transmitting portion. The manufacturing method of an optical sheet performed so that the supply amount of the composition for absorption parts may decrease. Each of the light absorbing portions has a first end face located on the light transmissive substrate side, and a second end face located on the side opposite to the first end face,
After forming the light absorbing portion, at least the second end surface of the light absorbing portion located at the end portion of the light transmitting portion is covered, and is made of a light transmitting resin. From the refractive index of the unit light transmitting portion, The method for producing an optical sheet according to claim 5, further comprising a step of forming a covering portion having a lower refractive index.   The method for producing an optical sheet according to claim 6, wherein the covering portion has a refractive index of 1.49 or more and 1.58 or less, and the light transmitting portion has a refractive index of 1.51 or more and 1.60 or less.

Images